1. Field of the Invention
The present invention relates to a sealing member for preventing escape of micro particles. More particularly, the present invention relates to a sealing member for preventing scattering of toner micro particles out from the gap between a magnet roller and housing of an electrophotographic copy machine that employs toner micro particles to obtain, for example, a vivid picture.
2. Description of the Background Art
Conventionally, a developing chamber (also called xe2x80x9cdeveloping devicexe2x80x9d) of an electrophotographic copy machine or a printer of office machinery is appropriately covered with a housing. Toner particles are applied onto a photoreceptor from a magnet roller charged with toner particles in the developing chamber to form a toner image. Then, a sheet is placed on the photoreceptor on which an image is formed, whereby the toner at the surface of the photoreceptor is transferred onto the sheet. At the housing region corresponding to the ends of the magnet roller at the bearing side, a sealing member is attached to seal the gap between the two ends of the magnet roller and the housing to prevent toner particles from escaping.
The conventional sealing member employs a layered structure of a wool and/or synthetic fiber felt or sponge adhered to a felt layer of fluorocarbon fiber (structure a), a velvet layer of fluorocarbon fiber (structure b), or a layered structure of a sponge layer adhered to a velvet layer of fluorocarbon fiber (structure c).
The aforementioned layered sealing member of xe2x80x9cstructure axe2x80x9d exhibits ravel and fall off as well as poor restoration of the fiber since the sliding region of the sealing member is formed of a felt layer. There was a problem that, when used over a long period of time, the sealing ability is degraded to result in escape of the toner particles. Furthermore, when attached to the curve face of the housing, the sliding region of the sealing member will be crimpled to form a gap through which toner particles will escape.
The aforementioned velvet layer sealing member of xe2x80x9cstructure bxe2x80x9d must have a flock length of at least 5 mm to seal the gap between the housing and the magnet roller. There was a problem that the cost is increased when fluorocarbon fiber is used.
The aforementioned layered sealing member of xe2x80x9cstructure cxe2x80x9d, when used for a developing chamber with toner of micro particles not more than 10xcexc, could not prevent such toner particles from escaping through the gap. It is to be noted that the toner micro particles used in electrophotographic copy machines and printers of office machinery directed to obtain a vivid picture are now as small as 10xcexc and below, for example, in particle size.
The present invention is directed to solve the above-described problems in conventional sealing members. An object of the present invention is to provide a sealing member exhibiting favorable retention and without the fall off of the flock of fiber brought into contact with a movable unit such as a magnet roller in contact with micro particles such as fine toner in a housing, and that has sufficient sealing ability to prevent escape of micro particles smaller than 10xcexc, for example, in particle size, without degrading the function of the movable unit.
The structure of the present invention is set forth below.
The sealing member of the present invention seals a predetermined gap between a movable unit that is brought into contact with micro particles and a housing of the movable unit, adhered to a face of the movable unit or housing to prevent escape of the micro particles without impeding the movement of the movable unit. The sealing member is based on a pile fabric configured with a pile yarn that forms a sliding flock and a base cloth of plain woven tissue supporting the pile yarn. The pile yarn of the flock is a high strength polyethylene fiber having a filament fineness of 0.1-6.0 dTex, a fiber cross section oblateness of at least 1.1, and an average tensile strength of at least 22 cN/dTex. The flock height is 1.5-4.0 mm. The pile density of the pile yarn region is 13,000-346,000 filament/cm2. The pile yarn cross section area per 1 cm2 of the base cloth, obtained from the following equation (1), is 0.02-0.2 cm2. The sealing member includes a coating layer at the back side of the base cloth to prevent the fall off of the flock.
S=fxc3x97d÷xcfx81÷1,000,000xe2x80x83xe2x80x83(1)
S: a pile yarn cross section area (cm2)
f: filament fineness of pile yarn (dTex)
d: pile density of flock (filament/cm2)
xcfx81: specific gravity of pile yarn (g/cm3)
According to the present invention, the sealing member is attached at the gap between the movable unit and the housing. The plain woven tissue and coating layer are flexible, and can easily be attached corresponding to the attaching configuration of the movable unit or housing. The pile yarn of the flock is supported by the plain woven tissue. The pile yarn is prevented from falling off by means of the coating layer. The gap between the movable unit and the housing is blocked by a pile yarn of 1.5-4.0 mm. The pile yarn with 0.1-6.0 dTex as the filament fineness, 13,000-346,000 filament/cm2 as the pile density at the pile yarn portion, and 0.02-0.2 cm2 as pile yarn cross section area per 1cm2 of the base cloth obtained from equation (1) can function to prevent escape of micro particles. The pile yarn is composed of a high strength polyethylene fiber having an average tensile strength of at least 22 cN/dTex. The pile yarn has a low abrasive coefficient and is resistant to abrasion, suitable to usage over a long period of time. Therefore, the sealing member of the present invention is superior in sidability and abrasion resistance.
According to another aspect of the present invention, the above sealing member has a cushion layer adhered to the bottom plane of the coating layer. The cushion layer is of 3-30 times foam and has a 25% compressive load value of 0.1-0.6 kg/cm2.
In the invention of the present aspect, attachment to the curved surface is further facilitated by the flexible cushion layer. In other words, the sealing member can be attached to the curved housing face without the plain woven tissue and coating layer being crimpled.
In the present invention, it is desirable that the pile yarns are brushed to be laid down in a predetermined direction.
In the present invention, a secure sealing layer is achieved since the group of pile yarns laid down in one direction captures micro particles within the group of pile yarns. The trapping of micro particles is facilitated by the lay down of the pile yarn to prevent micro particles from escaping. Since uneven lay down of the flock and the natural wave are eliminated by the brushing process, splitness is increased to result in stable sealing ability. Therefore, micro particles will not escape. The sealing ability is particularly favorable with respect to micro particles of 10xcexc and below.
As to the values of the filament fineness of the pile yarn that forms the flock, the flock height, and the flock pile density, the ranges set forth below were obtained as a result of testing the range in which toner of micro particles do not escape. In practice, the filament fineness of the pile yarn that forms the flock is preferably 0.1-6 dTex, and the fiber cross section oblateness is preferably at least 1.1. The height of flock is preferably in the range of 1.5-4.0 mm. A flock shorter than 1.5 mm offers difficulty in fabrication. Although the sealing property will not be degraded even if the flock is longer than 4.0 mm, the cost will be increased in such a case. The pile density of the flock is preferably in the range of 13,000-346,000 filament/cm2. The pile yarn cross section area per 1 cm2 of the base cloth, obtained from equation (1), is preferably in the range, of 0.02-0.2 cm2. If the pile density and the pile yarn cross section area are lower than 13,000 filament/cm2 and 0.02 cm2, respectively, micro particles will escape. If the pile density and the pile yarn cross section area are greater than 346,000 filament/cm2 and 0.2 cm2, respectively, the cost will be increased. Thus, the flock of the present invention is selected to be within the above practical ranges taking economical efficiency into account.
Polyurethane foam is employed for the cushion layer. This cushion layer must be flexible enough to be favorably adhered to the housing face. Based on tests, a cushion layer having the physical properties of 3-30 times foam, and a 25% compressive load value of 0.1-0.6 kg/cm2 was appropriate for the present invention. If the 25% compressive load value is lower than 0.1 kg/cm2, the cushion layer will be too soft. If the 25% compressive load value is higher than 0.6 kg/cm2, the cushion layer will be so hard that it cannot be easily bent. The cushion layer will not easily follow the curved housing face, resulting in degradation of the sealing property of the sealing member. The material of the cushion layer is not limited to polyurethane, and may include rubber, elastomer, and the like.
The lay down of the flock is effected by brushing down the flocks in a predetermined direction. By this brushing process, uneven lay down and waves in the yarn will be eliminated.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.